Ethanol And Fuels Questions

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Central Arkansastan
Here in the mid south, we seem to have two types of gas stations. Those who sell the 87/89/91, and those that sell 87/89/93.

Am I wrong is assuming that:

87 is 85 w/ethanol, the 89 is pure (no ethanol), and the 91 is 89 w/ethanol

and

87 is 85 w/ethanol, the 89 is max allowable ethanol, and the 93 is pure (no ethanol)?
 
Yes you are wrong. Different octanes can be sourced with OR without ethanol. Look at the pumps carefully. If a gasoline contains Ethanol they will be labeled, "contains x% Ethanol, and any Ethanol free gas these days will have a premium price over same octane rated gas containing ethanol.
 
I dont believe so. 87 is mostly 84-85 w/10% ethanol and 93 is what the marine industry calls Rec 90 with 10% ethanol and 89 is an at the pump blend of 87 and 93. Most stations dont want 3 tanks for gas so its easier to just get premium and reg and blend them. I dont know where the 91 comes from unless its mostly for high altitude stations that also sell 85 which have largely started to disappear since variable timing fuel injected engines.
 
This really, really depends on the state. I'd say, generally, you are not correct with that assumption.
Some states require gas WITH ethanol to be labeled, others only label gas withOUT ethanol.
If I remember correctly, Arkansas is a state that doesn't require labeling gas with ethanol. I'd assume that any gas you pump has it in unless you can confirm otherwise. Oh, and 93 would probably be the least likely to be pure from ethanol, with 91 being more likely (pure 91 + 10% ethanol = 93 octane)

For example, in MN we have:
-stations that are: 87/89/91, all with ethanol (HyVee, some Shell, Holiday, and Speedway come to mind)
-stations that are E-10 87/ E-10 89/ ethanol free 91 (with the 91 being labeled as ethanol-free) (usually Kwik Trip and/or stations near lake areas)
-stations with 87/89/92 or 93, all with ethanol (BP and Fleet Farm come to mind)
(as well as stations like Casey's or independents that may only sell 87)

From the stations I've gotten gas at in Arkansas (Exxon in Hope, Sunoco in Alma and a Murphy Express in Little Rock come to mind), I didn't remember seeing any sticker indicating the presence of ethanol at all. I assumed all of it was 10%; this would be like Minnesota. Stations in Iowa and Nebraska, on the other hand, usually label if the gas does or does not contain ethanol. Oftentimes there you'll see the following: non-ethanol 87, E10 87 (cheapest), and premium with or without ethanol (this is at many Kum and Gos, most HyVee's I've seen, some Casey's, some Shells, etc.) Other stations (e.g. Pilot/Love's, some Phillips 66, many BPs) have E-10 87/ 8-10 89/ usually E-0 91). Notable exceptions are certain stations (Sioux City Murphy USA comes to mind) where the midgrade is actually 91 E-10 and premium is 91 E-10.

The moral of the story: it really depends. Assume it probably has ethanol in it if it's not labeled. Hope that helps!
 
Originally Posted by Propflux01
Here in the mid south, we seem to have two types of gas stations. Those who sell the 87/89/91, and those that sell 87/89/93.

Am I wrong is assuming that:

87 is 85 w/ethanol, the 89 is pure (no ethanol), and the 91 is 89 w/ethanol

and

87 is 85 w/ethanol, the 89 is max allowable ethanol, and the 93 is pure (no ethanol)?



Here in Texas, DFW especially, the 87 and 93 have 10% ethanol like is advertised on the pumps.

I haven't tested any 89 or 91 yet, mostly 93 and some 87, and they definitely have the 10% ethanol.
 
Let's simplify it even more. Maybe you (Midstream) only want to have TWO tanks.

Let's also assume that 10% ethanol will add 3 octane numbers.

Now you can have 84 and 90 (or 91) octane tanks. Then 84 + eth = 87, 84+ 20%91 + 10% eth = 89, 90 +10 eth = 93. Done.

So maybe everybody is wrong?
 
Oh, I forgot. You can also "downgrade" 93 (NON-ETHANOL) with 84 so the blend for 91 might be a little different as might the 93 WITH 10% ethanol.

This is seen at the pumps that carry 93 octane non-ethanol fuel for recreational (boats) here in Florida. Using only two grades + Ethanol and the possibilities are nearly endless.
 
Originally Posted by samven
I dont believe so. 87 is mostly 84-85 w/10% ethanol and 93 is what the marine industry calls Rec 90 with 10% ethanol and 89 is an at the pump blend of 87 and 93. Most stations dont want 3 tanks for gas so its easier to just get premium and reg and blend them. I dont know where the 91 comes from unless its mostly for high altitude stations that also sell 85 which have largely started to disappear since variable timing fuel injected engines.

It would be a precise blend to achieve the final result with a specified concentration of oxygenate (typically ethanol). The most common base fuel on the commodity market is RBOB (reformulated blendstock for oxygenate blending). Whether or 89 is blended from on-site tanks or delivered as such depends on the site. I have never seen a Costco with midgrade. I guess they opted not to use a blending pump.

There was a time (a long time ago) when something like 87 octane at the pump would actually be 87 octane without ethanol and then have ethanol (or MTBE) blended which would boost the octane rating. Apparently this was called "octane giveaway".
 
The octane ratings on the pumps are minimums, it could very well be 87 octane with 10% ethanol which means there could also be 0%, and I believe that is the case, as the signs here all say "may contain up to 10% ethanol."

I'll have to get a graduated cylinder and actually test though. My 4am "let's use a pop bottle" method didn't work as good as I thought it would.
 
Originally Posted by Skippy722
The octane ratings on the pumps are minimums, it could very well be 87 octane with 10% ethanol which means there could also be 0%, and I believe that is the case, as the signs here all say "may contain up to 10% ethanol."

Unlikely though. There is a much higher demand for higher octane fuels these days. Even a lot of econoboxes specify "premium". It's hard enough meeting the demand for this with oxygenate to boost the octane rating. The ethanol may be optional, but the octane rating isn't. Ethanol is probably the most cost effective octane rating booster on the market - except maybe for lead which a nonstarter.

It may vary depending on the price of base gas, but fuel grade denatured ethanol is often cheaper than gasoline. It isn't now, but the current prices aren't likely to be long term. Even if it's slightly more expensive, some sort of oxygenate would likely be used simply because it's needed to boost the octane rating. MTBE would be ideal if it didn't make water taste foul. MTBE is superior to ethanol in many ways. It doesn't attract as much water and can be transported by pipeline. It does phase separate more easily because it doesn't have that affinity for water.
 
Quote
MTBE is superior to ethanol in many ways. It doesn't attract as much water and can be transported by pipeline. It does phase separate more easily because it doesn't have that affinity for water.


In my MTBE days, I hated that stuff. It would eat and swell VITON seals!
My friend used to transport it by tanker truck out in Colorado. Every delivery would end up short, missing several gallons of product. The investigation revealed that the stuff was seeping right through the sides of the aluminum trailer and evaporating!

He was driving along one day with a tailwind and passed out at the wheel of the tanker! No, I don't want to see that stuff ever again!
 
I have not seen gasoline without 10% ethanol since 2008 or so. I'd say your assumptions are totally wrong.
 
Up here in MN, you can still buy non-alcohol gasoline, but only in 91 octane premium. The intent of this fuel is for 2 stroke engines, and older engines without alcohol-resistant elastomers or AFI ratio-adjusting computers. They also charge an arm & a leg for it.

At a Cenex Coop in rural NW Wisconsin, they also sell non-alcohol gasoline in 87 octane. It is the only place I know of up here. I buy this for my small Briggs & Stratton engines, use the premium 91 octane for my 2-stroke outboards, snowmobile, chainsaws. 91 octane causes deposits in low compression flathead engines like B&S.
 
Originally Posted by RTexasF
I have not seen gasoline without 10% ethanol since 2008 or so. I'd say your assumptions are totally wrong.

It more a regional thing. The way gasoline is refined (and even made with cracking) really just makes several different fuel "streams" of different octane ratings. Of course ethanol is probably the easiest octane rating boost available, but it's not strictly needed if enough higher octane rated base fuel is used. Apparently some places there's 87 octane E0. In others it 91 E0. A few places it's even 93 E0. Sometimes it's sold alongside the same octane rating E10 at a higher price. But the key is that they're going to have a hard time making only E0 and meeting the demand for various fuels without having to discard some of the fuel for something else. The refiners want to be able to sell this fuel retailers.

This is kind of a weird market though. Fuel is fungible for the most part (California being very different because of the CARB requirements) and I guess they can play around with different availability in different parts of the country.
 
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